OP0167 ULTRASONOGRAPHY IN THE PREDICTION OF GOUT FLARES: A 12-MONTH PROSPECTIVE OBSERVATIONAL STUDY
Authors: E. Cipolletta, A. Abhishek, J. Di Battista, W. Grassi, E. Filippucci
Journal: Annals of the Rheumatic Diseases (2022)

Background Gout flares are a distinctive feature of gout. Although imaging techniques, such as ultrasonography (US), can visualise monosodium urate (MSU) crystals and synovial inflammation and estimate their burden, the role of imaging in predicting gout flares has not been fully investigated. Objectives To evaluate whether US findings indicative of MSU deposits and subclinical inflammation predict gout flares over 12 months. Methods Participants with gout on urate-lowering therapy (ULT) for at least the preceding six months were enrolled consecutively in this 12-month prospective, observational, single-centre study. A nested case-control analysis was performed. Cases were participants with at least one gout flare in the follow-up period while controls did not self-report any gout flares. Clinical assessment was scheduled at 6-month intervals. In addition, at baseline, each patient underwent an US examination using a standardised scanning protocol including the following sites: knees, ankles, 1 st metatarsophalangeal joints, elbows, wrists and 2 nd metacarpophalangeal joints. The US findings indicating MSU deposits [i.e., aggregates, double contour (DC) sign and tophi] and inflammation [i.e., Power Doppler (PD) signal] were identified according to the 2015 Outcome Measure in Rheumatology definitions (Figure 1). Figure 1. Summated scores were calculated for each US finding. During follow-up visits, patients were asked to report any gout flares using an internationally-validated definition [1]. Multivariate logistic regression analysis was used to measure the association between baseline US findings and the occurrence of gout flares over 12 months. US scores were tested separately, including the following covariates: age, gender, disease duration, presence of subcutaneous tophi, current serum urate&gt;360 μmol/l, increasing dose of ULT during the study period and ongoing flare prophylaxis. In addition, multivariate zero-inflated Poisson regression analysis was used to investigate the association between US findings and the number of flares over 12 months. Results Eighty-one gout participants were enrolled, and 71 completed the study. Thirty (42.3%) of 71 participants experienced at least one flare over 12 months, with a median of 2.0 flares. There was no difference among baseline clinical and laboratory characteristics of patients with and without flares except for the presence of subcutaneous tophi (23.3% vs 4.9%; p=0.02) and higher current SU levels (360.8 vs 301.4 μmol/l mol/L, p=0.01). Participants with flares had a greater baseline US burden of MSU deposits (2.0±1.8 vs 0.5±0.9, p=0.01 for DC sign; 2.1±2.3 vs 0.8±1.0, p=0.01 for tophi; 2.6±2.0 vs 1.6±1.6, p=0.03 for aggregates) and of subclinical inflammation (3.73±3.53 vs 0.82±1.44, p&lt;0.01). The baseline extent of MSU deposits and subclinical inflammation estimated by US was significantly associated with gout flares over 12 months in multivariate logistic regression analyses. DC sign score (aOR: 2.20, 95%CI: 1.22-4.34; p=0.01), tophi score (aOR: 2.16, 95%CI: 1.12-4.18; p=0.02) and PD score (aOR: 1.63, 95%CI: 1.12-2.40; p=0.01) predicted gout flares, whereas aggregates score (aOR: 1.40, 95%CI: 0.94-2.10; p=0.10) did not reach the statistical significance. Similar results were obtained in multivariate Poisson regression models (aIRR for DC score: 1.39, 95%CI: 1.18-1.64, p&lt;0.01, aIRR for tophi score: 1.30, 95%CI: 1.17-1.45, p&lt;0.01, aIRR for PD score: 1.29, 95%CI: 1.19-1.40, p&lt;0.01, aIRR for aggregates score: 1.13, 95%CI: 1.00-1.29, p=0.05). Conclusion Baseline US findings indicating MSU deposits and subclinical inflammation are independent predictors of gout flares over 12 months. References [1]Gaffo AL, et al. Brief Report: Validation of a Definition of Flare in Patients With Established Gout. Arthritis Rheumatol. 2018;70:462-7. Disclosure of Interests None declared